Fuel feed devices for internal combustion engines

ABSTRACT

The device comprises, in its intake pipe, a principal throttle member actuated by the driver, a source of fuel under pressure of which the delivery pipe which opens into the portion of the intake pipe situated downstream of the principal throttle member is controlled by at least one injection valve actuated by an electromagnet and a metering system which, provided with a rotary member driven in continuous rotation, is adapted to send into this electromagnet at least one energizing signal during a fraction of each revolution of said rotary member, regulated by this system. Electronic means supply a signal representing the measurement of the degree of opening of an auxiliary throttle member as a function of the variation in the flow-rate of air and a trigger signal appearing at each revolution of the rotary member. The electronic means comprise means for emitting, on each revolution of the rotary member, a first and a second saw-tooth signal, the saw-tooth of the second signal, in the course of one revolution of the rotary member, being triggered by the trigger signal and appearing after the saw-tooth of the first signal, this saw-tooth of the second signal having in addition a steeper slope than the slope of said saw-tooth of the first signal, the period t of this saw-tooth of the first signal corresponding substantially to the duration of a revolution of the rotary member, one of these saw-tooth signals having a slope variable as a function of the signal representative of the degree of opening of the auxiliary throttle member and the other of these two sawtooth signals having a generally constant slope. The electronic means includes a comparator to determine the fraction of each revolution of the rotary member which corresponds to the time that elapses between the beginning of the appearance of the sawtooth of steepest slope and the moment when the amplitude of this saw-tooth reaches that of the saw-tooth of the other signal. The electronic means is arranged so that the duration t of this fraction of a revolution is the duration of the energizing signal to be supplied to the electromagnet of the injection valve for each revolution of the rotary member.

} tln ited states Patent [191 Mennesson 1F UEL FEED DEVICES FOR INTERNAL COMBUSTION ENGINES [75] Inventor: Francois Paul Mennesson, Neuilly-sur-Seine, France [73] Assignee: Societe lndustrielle de Brevets Et 1 DEtudes S.I.B.E., Neuilly-sur-Seine,

France 22 Filed: .luly11,1972 211 App]. No.: 270,806

[30] Foreign Application Priority Data Primary Examiner-Laurence M.v Goodridge Assistant Examiner-Cort Flint Attorney, Agent, or Firm-Fleit, Gipple & Jacobson [57] ABSTRACT The device comprises, in its intake pipe, a principal throttle member actuated by the driver, a source of fuel under pressure of which the delivery pipe which opens into the portion of the intake pipe situated downstream of the principal throttle member is con- 11] 3,839,997 1 Oct. 8, 1974 trolled by at least one injection valve actuated by an electromagnet and a metering system which, provided with a rotary member driven in continuous rotation, is adapted to send into this electromagnet at least one energizing signal during a fraction of each revolution of said rotary member, regulated by this system. Electronic means supply a signal representing the measurement of the degree of opening of an auxiliary throttle member as a function of the variation in the flow-rate of air and atrigger signal appearing at each revolution of the rotary member. The electronic means comprise means for emitting, on each revolution of the rotary member, a first and asecond saw-tooth signal, the saw-tooth of the second signal, in the course of one revolution of the rotary member, being triggered bythe trigger signal and appearing after the saw-tooth of the first signal, this saw-tooth of the second signal having in addition a steeper slope than the slope of said saw-tooth of the first signal, the period t of this s awtooth of the first signal corresponding substantially to the duration of a revolution of the rotary member, one of these saw-tooth signals having a slope variable as a function of the signal representative of the degree of opening of the auxiliary throttle member arid the other of these two saw-tooth signals having a generally constant slope. The electronic means includes a comparator to determine the fraction of each revolution of the rotary member whichcorresponds to the time that elapses between the beginning of the appearance of the saw-tooth of steepest'slope and the moment when the amplitude of this saw-tooth reaches that of the saw-tooth of the other signal. The electronic means is arranged so that the duration 1 of this fraction of a revolution is the duration of the energizing signal to be supplied to the electromagnet of the injectionvalve for each revolution of the rotary member.

16 Claims, 3 Drawing Figures mimosa PATENTEB B B SHEET 2 [If 3 PATENTEB 9C? 74 PAIENTEBncI emu 3.889.997

sum anr The present invention relates to fuel feed devices for internal combustion engines.

More particularly it relates to such devices which comprise, on one hand, in their intake pipe, a principal throttle member actuated by the driver, on the other hand, a source of fuel under pressure whose delivery pipe which opens into the portion of the intake pipe situated downstream of the principal throttle member is controlled by at least one valve actuated by an electromagnet and on the other hand, lastly, a meteringsystem, provided with a rotary member driven in continuous movement, which is adapted to send into this electromagnet at least one energizing signal during a fraction of each revolution of said rotary member, said fraction being regulated by this system.

It is known that the regulation of this fraction of a turn determines, in a given interval of time, the total duration of opening of the valve, and, consequently, the flow-rate of fuel injected into the intake circuit during said interval of time.

The present improvements supplement those which have been disclosed by'Applicants prior application N 10,420 of Feb. 11, 1970 and its continuation and according to which, to provide the above-indicated ener' gizing signal, recourse is had to electronic means adapted to provide, on one hand, a signalrepresenting the measurement of the degree of opening of an auxiliary throttle member as a'function of the variation of the flow-rate of air,on the other hand, a trigger signal appearing on each revolution of the rotary member.

According to one embodiment, the trigger signal was obtained by the integration of pulses triggered on each revolution of the rotary member.

However the integration is not perfect and introduces a certain lack of precision into the calculation of the time of energization of the electromagnet. Moreover, this integrating circuit-requires a large number of electronic components and its price is high.

To overcome these drawbacks, according to themvention the above-said electronic means comprise means for emitting, on each revolution of the rotary member, a first and a second saw-tooth signal, the sawtooth of the second signal, in the course of one revolution of the rotary member, being triggered by the trigger signal and appearing after the saw-tooth of the first signal, this saw-tooth of the second signal having in addition a steeper slope thanthe slope of said saw-tooth of the first signal, the period T of this saw-tooth of the first signal corresponding substantially to the duration of one revolution of the rotary member, one of these saw-tooth signals having a variable slope as a function of the signal representative of the degree of opening of the auxiliary throttle member and the other of these two saw-tooth signals having a slope constant in principle, the above-said electronic means comprising, in addition, a comparator to determine the fraction of each revolution of the rotary member which corresponds to the time which elapses between the beginning of the appearance of the saw-tooth of greatest'slope and the moment when the amplitude of this saw tooth reaches that of the saw-tooth of the other signal, said electronic means being arranged so that the duration t of this fraction of a turn is the duration of the energizing signal to be supplied to the electromagnet of the injection valve for each revolution of the rotary member.

Preferably, the means for emitting the first and sec- 0nd saw-tooth signals are arranged so that the first sawtooth signal is of variable slope, the abovesaid electronic means comprising means for restoring toa given level, on each revolution of the rotary member,- the amplitude of the first and of the second signals as soon as the amplitude of the saw-tooth of the second signal has reached the amplitude of the saw-tooth of the first signal. 1

The two saw-tooth signals will be for example obtained by the charging of two capacitors in distinct appropriate generators, the charge of the capacitor of the generator of saw-teeth with variable slope being released by a triggering pulse emitted on each revolution of the rotary member, and its discharge effected, at the same time as that of the capacitor of the second generator, at the moment when the comparator registers equality of the voltages .of the two saw-teeth, a new constant slope saw-tooth being then emitted by recharging the corresponding capacitor, whilst the sawtooth of variable slope is only again triggered, by recharging of the corresponding capacitor, on the'following triggering pulse. I 4

' The electronic devices to be provided for the application of the foregoing features can be produced in numerous ways, and there will be given in the description whic'hfollo'ws one embodiment only by way of example; In particular, the second saw-tooth generatortthat of saw-teeth with variable slope), will be triggered by a pulse applied to abistable device,for example with several transistors. The energizing signal to be supplied to the electromagnet of the injection valve will then be modulated, as a'function of time, by a connection provided between the energizing circuit and one of the transistors of the bistable device, so that the energizing signal remains during the time t when said transistor is for example blocked, whilst it ceases during the period T-t, where said transistor is conductive.

A device arranged in the manner specified above indeed ensures, the delivery of an injection signal whose duration, on one hand, varies in the same sense as the degree of opening of the auxiliary throttle member (flow-rate of air) and on the other hand, is inversely proportional to the rotary speed of the rotary member, so that the amount of fuel injected during unit time is in fact independent of the speed of this member.

The invention consists, apart from these main features, of certain other features which are used preferably at the same time and which will be more explicitly discussed below, especially:

another feature according to which, to stop or limit the injection of fuel when the engine is decelerating, that is to say at a speed above that of idling, with the principal throttle member in its idling position, recourse is had to a supplementary comparator especially with transistors, which compares the saw-tooth voltage generated as a function of the speed of the aboveindicated rotary member (assumed coupled to the speed of the engine) to a reference voltage, the result of the comparison being brought to act, on the supply, so as to eliminatev the energizing signal of the electromagnet of the injection valve, whilst the speed is above that of idling. p

Thus the circuit of the energizing signal is combined withan AND gate with twoinputs one being connected to the transistor which normally defines the period t during which the said signal must be emitted, the other being connected to the abovesaid comparator, and the assembly being such that the signal can only be emitted if, on the two inputs and concurrently, there are applied voltages for example positive. If a period of deceleration is not taking place, this simultaneous presence exists in the course of the successive intervals of time t. If a period of deceleration is occurring, this simultaneous presence cannot be produced since there is always, on a terminal connected to the comparator, a voltage for example a low voltage.

The invention relates more particularly to certain types of application (especially that for which it is applied to devices of the type concerned for vehicle engines), as well as certain embodiments, of said features; and it relates, more particularly also and this by way of new industrial products, to devices of the type concerned, comprising the application of these same features, as well as the special elements adapted to their construction and engines and assemblies comprising them.

the ivention will, in any case, be well understood with the aid of the supplementary description which follows, as well as of the accompanying drawings, which supplement and drawings are, of course, given particularly by way of illustrative but non-limiting example.

In the drawings:

FIG. 1 is the diagram of a feed device, for an engine, constructed according to the invention.

FIG. 2 is a diagram of the electronic portion of such a device, according to one of the embodiments capable of being adopted.

FIG. 3, lastly, shows various diagrams illustrating the operation of this circuit.

According to the invention, and more especially according to that of its types of application, as well as according to those embodiments of its various parts, to which it seems that preference should be given, in order for example to construct a fuel feed device for a vehicle engine or the like, precedure is as follows or in analogous manner.

This device is firstly made to comprise, and as already known, especially according to Applicants prior Pat. application Ser. N 10,420 of Feb. 1 l, 1970, an intake pipe 1, in which are arranged, on one hand, a principal throttle member 2, (connected to a manual or pedal acceleration control) an auxiliary throttle member 3 actuated for example by pneumatic means 52, so that its position is characteristic of the flow of air passing in the pipe 1. These pneumatic means can be of any suitable type, especially such as described in said Patent application Ser. N 10,420. The said auxiliary throttle member could besides be replaced by any technical equivalent, especially those described in French Patent N 1,546,748 and its Certificates of Addition.

Then, having this assembly, there is applied to it, as an electronic control device 7 (FIGS. 1 and 2):

on one hand, triggering pulses, applied to an input of the device 7 and coming from a device 9 influenced by the rotation of a rotary member 10 such as described in the above-said principal patent, which member is driven for example, as will be assumed below, by the engine,

and on the other hand, a signal of variable potential applied on an input 6 of said device 7 and as a function of the position of the auxiliary throttle member 3, this member controlling for example, by a cam 50 and r0! ler 51, the slider of a variable resistance 4 connected to a source of constant voltage 5,

the electronic control device 7 being adapted to supply an injection signal to an output terminal 11, which signal is then amplified by an amplifier l2 and sent into the electromagnet of an injection valve or injector l3 supplied with fuel from a source of fuel under pressure As far as the electronic device 7 is concerned, more especially, for supplying the injection signal variable as a function of the information received on its input 6 and 8, it is arranged in such a way that:

a second generator supplies the first saw-tooth signals triggered on each pulse coming from the rotary member 10, that is to say on each revolution of the latter, each of the saw-teeth thus obtained having a variable slope as a function of the information coming from the auxiliary throttle member and received on the input 6 (signals in the form of saw-teeth such as represented by a diagram B, FIG. 3),

a first generator supplies second saw tooth signals with constant slope and of duration corresponding to each period T of rotation of the rotary member (signals such as represented by diagram C, FIG. 3),

these two signals in the form of saw-teeth are applied to a comparator arranged so that the value of each second saw-tooth signal (type B) is brought to a given level (preferably zero) at the moment when this value reaches the value of the first saw-tooth signal of type C (voltage A, FIG. 3), which is produced after a time t, of each period T, which is only a function of the information received on the input 6,

and suitable means ensure the emission of a control signal of pre-deterrnined amplitude b during each time t, which signal is applied on the output 11 and represented diagramatically at F in FIG. 3.

The control of the first of the two generators, from pulses of the type represented in diagram A of FIG. 3, is obtained by means of any suitable electronic switch, especially a transistor flip-flop device.

It is self-evident that the features which have been specified, regarding the control device 7 of FIG. 1, can be constructed in many ways. Generally, the slope of the saw-tooth signals is obtained by the charging of a capacitor due to a constant current and its discharge. For the teeth of type B, the slope is made variable by the effect of the variable resistance 4 or any equivalent member.

There will, in the following, bedescribed an embodiment, solely by way of example, and illustrated in FIG. 2, where the points A, B, C, D, E and F correspond to voltage signals with the same references, of FIG. 3.

The assembly comprises firstly a bistable flip-flop,

represented in detail at 14 in FIG. 2, and comprising transistors T and T adapted to coact with the generator 15 of the sawteeth B, such as described below, bistable flip-flop on which there is applied, at the input 8, the pulses caused by the rotation of the rotary member 10.

These pulses are first treated for example in a derivator system or the like, with a capacitor 20, resistance 58 and diode 21, so as to obtain at the point A steep front pulses such as represented in diagram A of FIG. 3

Each pulse of type A is transmitted to the base of the transistor T which, from the conductive state in which it is initially, passes to the blocked state. Through this fact, the transistor T which was initially blocked, becomes conductive and acts on the generator (FIGS; 1 and 2) of the saw-teeth B.

This generator 15 of saw-teeth B, of which teeth the slope is variable, comprises for example essentially a transistor T mounted in a constant current generator, in combination with a circuit, comprising a resistance 55, a capacitor 56 and a diode 57, connected to its base, whilst its two other electrodes are respectively connected, one to the point 6 at which the circuit of the variable resistance 4 ends, the other at B with a capacitor 22. The said generator comprises, in addition, a transistor T which serves to receive the pulse supplied by the bistable flip-flop thereby ensuring, either, in its blocked state, the charging of the capacitor 22 by the transistor T.,, or, as soon as the said transistor T has again become conductive, the discharge of this capacitor.

It is seen therefore, here and now, that the emission of a triggering pulse A, by rendering the transistor T conductive, has the effect of blocking the transistor T which brings into play the charge of the capacitor 22 under the action of the transistor T4, this charge being produced until an order to stop and. discharge is given by the comparator, as described below.

It is convenient also, in this first generator, to fix the minimum value'of the voltage at point B, when the capacitor 22 is discharged; this is achieved for example by means of a Zener diode 24, protected by a capacitor 23. This base potential will for example be'three volts at-the terminal 34 of the capacitor 22.

In any case,the generator 15 which has just been described or any other leading to the same result and which is at the disposal of the skilled technician to use ensures, in combination with a capacitor 22 and the variable resistance 4, the formation of the variable slope saw-teeth of the type B which, through a transis tor such as T are sent to the comparator 16 described below. i i

The transistor T is provided to limit the drain of current from point B to the comparator, whilst ensuring, on its emitter, a suitable current for the transmission of the saw-tooth B to the comparator 16..

Now as regards the second generator 17, it comprises of the NPN type, of which the emitters have a common terminal 25, connected to the collector of a transistor T mounted in a constant current generator, with a resistance 59, a capacitor 60 and a Zener diode 61.

Normally, the transistor T "is conductive and the transistor T is blocked.

The comparison is then effected in the following way.

When the voltage at point B increases, there arrives a moment when the voltage on the base of the transis' tor T is at least equal to that of the base of the transistor T, (subjected to the action of the second generator 17). The transistor T then becomes conductive, which itial position. To this end for example, the amplified signal-coming from said transistors is brought, through a capacitor 27 and a diode 28, to the transistor T of the bistable element 14, which transistor is'brought back then into its initial blocked state, so that the transistor v T5 again becomes conductive, and short-circuits the capacitor 22 which is discharged.

As regards the discharge of the capacitor 33, and its gradual recharging under the action of the transistor T a'pulse D is used, amplified by the transistor system T and T to generate, for example through another monostable flip-flop 18, a pulse E of suitable sense and for example a constant current generator comprising a transistor T adapted to charge a capacitor 33-through a pre-determined resistance 54, which could however vary according to certain characteristics of the internal combustion engine, for example its temperature.

With this transistor T cooperates, in addition, a transistor T13 adapted, by being connected in the manner indicated below and from the signalemitted by the comparator, to ensure the discharge of the capacitor 33, this transistor T being mounted at the terminals of the latter, so that, when it is rendered conductive-and during the time when it remains conductive, it short-- circuits the said capacitor.

It is hence seen that the generator thus constructed ensures the formation of a signal of type C, for example at the point indicated at C on the collector of the transistor T (in the assembly shown), this signal being sent into the comparator 16, through a transistor T which plays the same role as the transistor T in the first generator l5.

Now as regards the comparator 16, it is made for example to comprise two transistors T and T especially of which the duration is sufficient to ensure the discharge of the capacitor 33. In fact, the curves of FIG. 3 are theoretical and, in reality, the side such as mn corresponding to the discharge is not absolutely straight, the discharge requiring a certain time t It is to this time that the pulse E must correspond.

The monostable flip-flop 18 comprises for example two transistor T and T receiving the pulse D amplified by the system T and T through a capacitor 29 and a diode 30, said flip-flop being of known assembly, with a capacitor 31 and a discharge resistor 32, these two latter elements fixing the duration r of thepulse E thus generated. This pulse is transmitted to the transistor T which ensures the dischargeof the capacitor 33, which discharge corresponds to the trailing edge of the saw-tooth C. Immediately after time t,,, the transistor T isblocked again and the following saw-tooth-C starts by the recharging of the capacitor 33 by means of thetransistor T and so on. 7

It is to be noted that the voltage at the terminal 25 is at minimum equal to .the saturation voltage of the transistor T,,. It is hence necessary, for the comparator 16 to function, for the minimal voltages at points B and C,

when the capacitors 22 and 33aredischarged, to be at least equal to the minimum voltage of the terminal 25. This is why the Zener diode 24 fixes a minimum potential of about 3 volts, as indicated above, at terminal 34.

This time t is then utilised, in any suitable manner, to generate a control pulse F (FIG. 3) of suitable amplitude b, this pulse being followed by a dead period, that is to say the time following T-t, and so on.

One embodiment, among others possible, to generate this energizing signal F, consists, on one hand, in connecting the point F and the output terminal 11 to the pole of the battery 5 (plus pole in the embodiment shown) with a resistance 58a, and on the other hand, to connect also said point, for example through a diode 39, to the collector of the transistor T,, of the bistable element 14. During the time t, said transistor is blocked, so that its collector applies a positive voltage to point F, on the other hand, on deblocking this transistor during the time T4, a by-pass is produced through the latter, and the voltage at point F falls to zero or, in any case, diminishes.

There is hence finally obtained a device for metering fuel independently of speed, since what counts is the ratio t/T, which only depends on the slope of the sawtooth B. In fact, if the slopes of the saw-teeth B and C are denoted by, respectively, B and 'y, there may be written (FIG. 3):

B mn/t and 'y mn/t,

whence there results:

the flow-rate of air (hence the slope [3) remaining constant, if the period T varies (by variation of the speed of rotation of the rotary member said ratio t/T will remain constant and it will be the same for the amount of fuel injected per unit time.

It is to be noted that, if in the embodiment described it is assumed that the saw-teeth C has a constant slope and saw-tooth B a slope variable as a function of the flow-rate of air, the reverse case can be envisaged in which the saw-tooth B has a constant slope and the saw-tooth C a variable slope.

In the case illustrated in the drawing, the electromagnet of the injection valve 13 receives square pulses, such as shown in FIG. 3, of amplitude b and of duration t.

It is convenient however to complete the preceding assembly with suitable means to eliminate the energizing signal at terminal F, 11, in the case where the engine is in a period of deceleration, the principal throttle member being in its idling position and the speed of the engine diminishing to its idling speed.

These means, according to an advantageous feature of the invention, consist of a comparator 19 adapted to compare, on one hand, the voltage of the saw-tooth C and on the other hand, a pre-determined reference voltage, to give a correction signal preventing the production of the signal F.

It is noted in fact that the maximum voltage A of each saw-tooth of type C is inversely proportional to the speed, if the rotary member 10 is assumed to be connected with the speed of the engine. When the speed of the engine decreases, this voltage rises. It can hence be arranged that, when the engine again arrives at idling speed, the voltage a, in increasing, becomes equal to a reference value selected to be sufficiently high, and at this moment, the comparator brings into play a signal re-establishing injection.

The comparator concerned 19 will in any case be controlled by a switch 40 adapted to be closed when the principal throttle member 2 reaches its idling position, said comparator only being able to act in this case.

It will consist for example of three transistors T T and T acting in similar manner to that of the three transistors of comparator 16. The transistor T receives at its base the voltage of the saw-tooth C, delivered by the transistor T whilst transistor T receives at its base the given reference voltage at terminal 41 connected to said base, through resistances 42 and 43, if necessary adjustable.

This voltage will for example be selected so that, for a speed of the rotary member 10 which is assumed connected to the speed of the engine equal or slightly greater than the selected speed for idling, said voltage is at least equal or greater than the maximum of the voltage a. I

It will hence be observed that for all low values of the maximum a of the voltage C, the transistor T will be for example rendered conductive, enabling thus the application of a correction signal preventing injection, and that until, as a result of the deceleration, the voltage a increases sufficiently to equal the reference voltage and re-establish injection.

As regards the manner of operating this correction, recourse will advantageously be had, in the energizing circuit, at F, 11, to an AND gate 35 with two inputs corresponding, one 37, to the connection with the collector of the transistor T (in the embodiment adopted), the other 36, to a connection with the circuit of the switch 40 and of the comparator 19.

This gate is formed for example by two diodes 38 and 39 (of which that 39 already mentioned above), of which the respective cathodes 36 and 37 are connected respectively to the comparator l9 and to the transistor It is seen that under these conditions the energizing pulses F, B (FIG. 3) to the electromagnet of the injector, can only be presented when, on terminals 36 and 37, there concurrently occur positive voltages.

This will be the case when the switch 40 is open, that is to say outside idling speed operation. In fact, the comparator 19 being out of circuit, the terminal 36 remains positive. It is the same with the terminal 37, during the intervals t when the transistor T is blocked.

On the other hand, in the case of deceleration, the switch 40 being closed the terminal 36 becomes less positive as a result of the placing of the transistor T in the conductive condition.

This correction effect, inhibiting injection, will last until the speed being brought back to that of idling, and the voltage a having thus rejoined the reference voltage, the transistor T will be blocked, the terminal 36 thus taking up a high potential. The injection can then be resumed to maintain idling.

As a result of which, whatever the embodiment adopted, there can thus be obtained a feed device of which the operation emerges sufficiently from the foregoing for it to be unnecessary to dwell further on this subject and which enables the delivery of an injection signal of which the duration, on one hand, varies in the same senwe as the degree of opening of the auxiliary throttle member, and, on the other hand, is inversely proportional to the speed of rotation of the rotary member..

In other words, for a given position of the auxiliary throttle member, the fraction of a revolution of the rotary member during which injection occurs, is independent of the speed of rotation of the rotary member.

in addition, the device enables the stopping of injection on deceleration.

Such a device has numerous advantages, especially: that of only requiring relatively simple circuits, that of giving rise to high precision, and that of offering full safety.

Asif self evident, and as emerges already from the foregoing, the invention is in no way limited to those of its types of application and embodiments which have been more especially envisaged; it encompasses, on the contrary, all modifications.

I claim:

l. The combination for feeding fuel to an internal combustion engine comprising:

A. an intake pipe for the internal combustion engine;

B. an operator-actuated main throttle member positioned in the intake pipe;

C. a source of fuel under pressure;

D. delivery conduit means connected to said source of fuel for delivering same to said intake pipe at a point downstream of said main throttle member;

E. an injection valve controlling the delivery of fuel to said intake pipe via said delivery conduit means;

F. electromagnetic means for actuating said injection valve; and

G. metering and control means to supply a control signal to said electromagnetic means comprising: a. an auxiliary throttle member positioned in said intake pipe,

b. throttling means operatively connected with said auxiliary throttle member to control the degree of opening of the latter responsive to air flow in said intake pipe,

c. a continuously driven rotary member,

d. electronic means for generating said control signal during a fraction of each revolution of said rotary member representative of said degree of opening of said auxiliary throttle member and a trigger signal generated during each revolution of the rotary member, said electronic means comprising:

i. means for generating first and second sawtooth signals with the second saw-tooth signal being triggered by said trigger signal and char acterized by a steeper slope than that of said first saw-tooth signal,

ii. the period T of said first saw-tooth signal being substantially equal to the duration of a revolution of said rotary member,

iii. one of said saw-tooth signals having a slope variable responsive to the degree of opening of said auxiliary throttle member and the other of said saw-tooth signals having a substantially constant slope,

iv. comparator means to compare said saw-tooth signals and to restart said first saw-tooth signal responsive to the amplitudes of thesaw-tooth signals being equal and to generate said control signal of a time duration equal to the interval between said trigger signal and restarting of said first saw-tooth signal, and

v. means to apply said control signal to said electromagnetic means to actuate same and hence allow fuel to be delivered through said injection valve into said intake pipe for the duration of said control signal.

2. Device according to claim 1, wherein the means for emitting the first and the second saw-tooth signals are arranged so that the first saw-tooth signal is of constant slope and the second signal is of variable slope, the abovesaid electronic means comprising means to restore to a given level, on each revolution of the rotary member, the amplitude of the first and of the second signals as soon as the amplitude of the saw-tooth of the second signal has reached the amplitude of the sawtooth of the first signal.

3. Device according to claim 2, comprising two distinct generators, each including a capacitor, each sawtooth signal being obtained by the charging of a capacitor, the charge of the capacitor of the generator of variable slope saw-teeth being triggered by the trigger signal emitted on each revolution of the rotary member, and its discharge effected, at the same time as that of the capacitor of the second generator, at the moment when the comparator registers the equality of the amplitudes of the two saw-teeth, a new saw-toothof constant slope beingthen emitted by recharging of the corresponding capacitor, whilst the saw-tooth of variable slope is only again triggered, by recharging of the corresponding capcitor, on the appearance of the following trigger signal.

4. Deviceaccording-to claim 2, wherein said electronicmeans comprise means for emitting a pulse on each revolution of the rotary member and a bistable flip-flopadapted to deliver the trigger signal, said pulse being applied to an input of said flip-flop, the electronic means being arranged so that the bistable flip-flop delivers, at each of its outputs, a signal of given level, during the abovesaid duration 1, this signal of given level being utilised by an energizing circuit to supply the said energizing signal of the electromagnet exclusively during the duration t, on each revolution of the rotary member.

5. Device according to claim 2, wherein the generator of variable slope saw-teeth comprises a transistor mounted in a constant current generator and adapted to charge a'capacitor through a resistance of value variable as a function of the position of the auxiliary throttle member, in combination with a control transistor which, when it is blocked, ensures the charging of the capacitor and, when it is conductive, ensures the discharging of said capacitor.

6. Device according to claim 4, wherein, to obtain a steep. front pulse, the means for emitting a pulse on each revolution of the rotary member comprise deriving means of which the output furnishes said pulse, said bistable flip-flop comprising two transistors of which the first is initially conductive and the second initially blocked, this second transistor being itself connected to the control transistor of the generator of variable slope saw-teeth so thatsaid pulse enables the blocking of the first transistor, the rendering conductive of the second transistor and the blocking of the said control transistor in order to ensure the charging of the capacitor of the said generator of variable slope saw-teeth.

7. Device according to claim 4, wherein the energizing circuit comprises an AND gate and at least onev input connected to the output of the bistable flip-flop ing said duration t.

8. Device according to claim 4, wherein the comparator is arranged to supply a discharge pulse when the amplitudes of the two saw-teeth signals are equal and the bistable flip-flop comprises an input adapted to receive said discharge pulse so that the output of this flipflop changes state.

9. Device according to claim 2, wherein the generator of constant slope saw-teeth comprises a transistor mounted in a constant current generator, adapted to charge a second capacitor, in combination with a transistor provided for the discharge of this second capacitor, this discharge transistor being rendered conductive by the action of a control pulse released, due to the comparator, at the end of the duration t and of sufficient length to ensure the discharge of the said second capacitor, followed at once by its continuous recharging at constant slope.

10. Device according to claim 2, wherein the comparator adapted to utilise the two saw-teeth signalscomprises essentially two transistors connected through their emittors to a common terminal, one of these two transistors, initially blocked, becoming conductive when the amplitudes of the two saw-teeth signals to be compared become equal, which ensures the emission of a discharge pulse used for the discharge of the capacitors of the generators.

11. Device according to claim 8, wherein the electronic means comprise a mono-stable flip-flop comprising an input adapted to receive said discharge pulse and an output which, when said input receives said pulse, delivers a pulse E of sufficient duration for, being applied to the discharge transistor, ensuring the discharge of the capacitor of the generator of constant slope sawtooth signals, after which a new saw-tooth is again generated.

12. Device according to claim 11, wherein the monostable flip-flop comprises two transistors. a capacitor and a resistance, this resistance being arranged to enable the discharge of the said capacitor through it, the value of this resistance and the capacity of this capacitor determining the duration of the pulse E.

13. Device according to claim 2, comprising means to enable, when the principal throttle member is in its slow speed position, and the engine is decelerating, the elimination of the energizing signal for the electromagnet, these means utilising a signal coming from a supplementary comparator effecting comparison between the maximum level, inversely proportional to the speed, of the constant slope saw-tooth, on one hand, and a reference voltage, on the other hand.

14. Device according to claim 13, arranged so that the value of said reference voltage for a value of the speed of the rotary member slightly greater than that corresponding to idling, is at least equal to the maximum voltage a of the constant slope saw-teeth.

15. Device according to claim 14, comprising a switch controlled, as a function of the movements of the principal throttle member, so that the supplementary comparator only intervenes on the closing of said switch, said supplementary comparator comprising two transistors, one of these transistors receiving the sawtooth signal to be compared and the other of these transistors receiving the reference signal emitted by the means enabling the adjustment of the value of this signal.

16.'Device according to claim 7, wherein the AND gate of the energizing circuit comprises two inputs, the second of these inputs being connected to a supplementary comparator, through said switch. 

1. The combination for feeding fuel to an internal combustion engine comprising: A. an intake pipe for the internal combustion engine; B. an operator-actuated main throttle member positioned in the intake pipe; C. a source of fuel under pressure; D. delivery conduit means connected to said source of fuel for delivering same to said intake pipe at a point downstream of said main throttle member; E. an injection valve controlling the delivery of fuel to said intake pipe via said delivery conduit means; F. electromagnetic means for actuating said injection valve; and G. metering and control means to supply a control signal to said electromagnetic means comprising: a. an auxiliary throttle member positioned in said intake pipe, b. throttling means operatively connected with said auxiliary throttle member to control the degree of opening of the latter responsive to air flow in said intake pipe, c. a continuously driven rotary member, d. electronic means for generating said control signal during a fraction of each revolution of said rotary member representative of said degree of opening of said auxiliary throttle member and a trigger signal generated during each revolution of the rotary member, said electronic means comprising: i. means for generating first and second saw-tooth signals with the second saw-tooth signal being triggered by said trigger signal and characterized by a steeper slope than that of said first saw-tooth signal, ii. the period T of said first saw-tooth signal being substantially equal to the duration of a revolution of said rotary member, iii. one of said saw-tooth signals having a slope variable responsive to the degree of opening of said auxiliary throttle member and the other of said saw-tooth signals having a substantially constant slope, iv. comparator means to compare said saw-tooth signals and to restart said first saw-tooth signal responsive to the amplitudes of the saw-tooth signals being equal and to generate said control signal of a time duration equal to the interval between said trigger signal and restarting of said first saw-tooth signal, and v. means to apply said control signal to said electromagnetic means to actuate same and hence allow fuel to be delivered through said injection valve into said intake pipe for the duration of said control signal.
 2. Device according to claim 1, wherein the means for emitting the first and the second saw-tooth signals are arranged so that the first saw-tooth signal is of constant slope and the second signal is of variable slope, the abovesaid electronic means comprising means to restore to a given level, on each revolution of the rotary member, the amplitude of the first and of the second signals as soon as the amplitude of the saw-tooth of the second signal has reached the amplitude of the saw-tooth of the first signal.
 3. Device according to claim 2, comprising two distinct generators, each including a capacitor, each saw-tooth signal being obtained by the charging of a capacitor, the charge of the capacitor of the generator of variable slope saw-teeth being triggered by the trigger signal emitted on each revolution of the rotary member, and its discharge effected, at the same time as that of the capacitor of the second generator, at the moment when the comparator registers the equality of the amplitudes of the two saw-teeth, a new saw-tooth of constant slope being then emitted by recharging of the corresponding capacitor, whilst the saw-tooth of variable slope is only again triggered, by recharging of the corresponding capcitor, on the appearance of the following trigger signal.
 4. Device according to claim 2, wherein said electronic means comprise means for emitting a pulse on each revolution of the rotary member and a bistable flip-flop adapted to deliver the trigger signal, said pulse being applied to an input of said flip-flop, the electronic means being arranged so that the bistable flip-flop delivers, at each of its outputs, a signal of given level, during the abovesaid duration t, this signal of given level being utilised by an energizing circuit to supply the said energizing signal of the electromagnet exclusively during the duration t, on each revolution of the rotary member.
 5. Device according to claim 2, wherein the generator of variable slope saw-teeth comprises a transistor mounted in a constant current generator and adapted to charge a capacitor through a resistance of value variable as a function oF the position of the auxiliary throttle member, in combination with a control transistor which, when it is blocked, ensures the charging of the capacitor and, when it is conductive, ensures the discharging of said capacitor.
 6. Device according to claim 4, wherein, to obtain a steep front pulse, the means for emitting a pulse on each revolution of the rotary member comprise deriving means of which the output furnishes said pulse, said bistable flip-flop comprising two transistors of which the first is initially conductive and the second initially blocked, this second transistor being itself connected to the control transistor of the generator of variable slope saw-teeth so that said pulse enables the blocking of the first transistor, the rendering conductive of the second transistor and the blocking of the said control transistor in order to ensure the charging of the capacitor of the said generator of variable slope saw-teeth.
 7. Device according to claim 4, wherein the energizing circuit comprises an AND gate and at least one input connected to the output of the bistable flip-flop which delivers the signal of given level exclusively during said duration t.
 8. Device according to claim 4, wherein the comparator is arranged to supply a discharge pulse when the amplitudes of the two saw-teeth signals are equal and the bistable flip-flop comprises an input adapted to receive said discharge pulse so that the output of this flip-flop changes state.
 9. Device according to claim 2, wherein the generator of constant slope saw-teeth comprises a transistor mounted in a constant current generator, adapted to charge a second capacitor, in combination with a transistor provided for the discharge of this second capacitor, this discharge transistor being rendered conductive by the action of a control pulse released, due to the comparator, at the end of the duration t and of sufficient length to ensure the discharge of the said second capacitor, followed at once by its continuous recharging at constant slope.
 10. Device according to claim 2, wherein the comparator adapted to utilise the two saw-teeth signals comprises essentially two transistors connected through their emittors to a common terminal, one of these two transistors, initially blocked, becoming conductive when the amplitudes of the two saw-teeth signals to be compared become equal, which ensures the emission of a discharge pulse used for the discharge of the capacitors of the generators.
 11. Device according to claim 8, wherein the electronic means comprise a mono-stable flip-flop comprising an input adapted to receive said discharge pulse and an output which, when said input receives said pulse, delivers a pulse E of sufficient duration for, being applied to the discharge transistor, ensuring the discharge of the capacitor of the generator of constant slope saw-tooth signals, after which a new saw-tooth is again generated.
 12. Device according to claim 11, wherein the monostable flip-flop comprises two transistors, a capacitor and a resistance, this resistance being arranged to enable the discharge of the said capacitor through it, the value of this resistance and the capacity of this capacitor determining the duration of the pulse E.
 13. Device according to claim 2, comprising means to enable, when the principal throttle member is in its slow speed position, and the engine is decelerating, the elimination of the energizing signal for the electromagnet, these means utilising a signal coming from a supplementary comparator effecting comparison between the maximum level, inversely proportional to the speed, of the constant slope saw-tooth, on one hand, and a reference voltage, on the other hand.
 14. Device according to claim 13, arranged so that the value of said reference voltage for a value of the speed of the rotary member slightly greater than that corresponding to idling, is at least equal to the maximum voltage a of the constant slope saw-teeth.
 15. Device according to claim 14, compriSing a switch controlled, as a function of the movements of the principal throttle member, so that the supplementary comparator only intervenes on the closing of said switch, said supplementary comparator comprising two transistors, one of these transistors receiving the saw-tooth signal to be compared and the other of these transistors receiving the reference signal emitted by the means enabling the adjustment of the value of this signal.
 16. Device according to claim 7, wherein the AND gate of the energizing circuit comprises two inputs, the second of these inputs being connected to a supplementary comparator, through said switch. 